Transverse drive transmissions have a drive mechanism, either chain or gearing, to transfer the power from the engine axis to the output axis. When the torque converter is on the engine axis and the planetary gear arrangement is on the output axis, a chain drive is generally used to join the two axes. When the planetary gearing torque converter and engine are on the same axis, the transfer gear assembly is often used to transfer rotation and power to the output shaft. Transmissions of this type have also suggested using a chain drive between the planetary output and the transmission final drive.
When a transfer gear drive mechanism is used, an idler gear is employed to provide the proper rotation direction for the forward and reverse drives. The idler gear use causes an increase in the distance between the two axes and they also affect the overall size of the transmission housing. The idler gear also requires that accommodations be made for supporting the idler gear within the transmission housing.
In some transmission designs, the third axis, that is the idler gear axis, is also used or shared with a third axis for the gearing. However, the idler gear type design is usually less space efficient than a two axis design. Also, the alignment of three parallel axes is usually more difficult than that of two parallel axes.
In the prior art, the use of a chain drive between various gear elements has eliminated the need for the third axis, however, the use of a chain drive determines the load carrying capacity of the transmission. In some instances, it may be desired to provide higher torque and power transmission than the chain drive is designed to accept, in which case, the gear system is utilized.